linux-kernel - Re: [STLinux Kernel] [PATCH 0/4] clk: Provide support for always-on clocks

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Date:	Thu, 2 Apr 2015 09:12:10 +0100
From:	Peter Griffin <peter.griffin@...aro.org>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	mturquette@...aro.org, sboyd@...eaurora.org, kernel@...inux.com,
	devicetree@...r.kernel.org
Subject: Re: [STLinux Kernel] [PATCH 0/4] clk: Provide support for always-on
 clocks

Hi Lee,

On Fri, 27 Feb 2015, Lee Jones wrote:

> Some hardware contains bunches of clocks which must never be
> turned off.  If drivers a) fail to obtain a reference to any
> of these or b) give up a previously obtained reference
> during suspend, the common clk framework will attempt to
> disable them and a platform can fail irrecoverably as a
> result.  Usually the only way to recover from these failures
> is to reboot.
> 
> To avoid either of these two scenarios from catastrophically
> disabling an otherwise perfectly healthy running system,
> clocks can be identified as always-on using this property
> from inside a clocksource's node.  The CLK_IGNORE_UNUSED
> flag will be applied to each clock instance named in this
> property, thus preventing them from being shut down by the
> framework.

Great stuff.

One minor comment is that assuming this works on stih407 and stih410
to the extent that the platform can now boot without clk_ignore_unused
kenel parameter then you should have an additional patch to remove
clk_ignore_unused from the default bootargs in stih407-b2120.dts and
stih410-b2120.dts files.

Maxime - Is it possible for you to test this series on stih418-b2199 as
a well? As it could most likely also be removed from stih418-b2199.dts file
to, but neither Lee or myself have the hardware to test.

Apart from that, for the series: -
 Acked-by: Peter Griffin <peter.griffin@...aro.org>

regards,

Peter.
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